<?php
namespace app\model;

use think\Db;

class Express extends Common
{
    protected static $obj;

    public function _initialize()
    {
        parent::_initialize();
        $this->db_name = 'express';
    }

    /**
     * 类入口
     * @return Express
     */
    public static function getInstance()
    {
        if (is_null(self::$obj))
            self::$obj = new self();
        return self::$obj;

    }

    /**
     * 快递公司名称
     */
    public function getExpressName($express_id){
        return Db::name($this->db_name)
            ->where($express_id)
            ->value('express_name');
    }
}
